Accelerator



Patented Mar. 19, 1935 UNITED ST 'QFFICE ACCELERATOR Delaware 'No Drawing.

It is well known that the mercaptothiazoles generally, and particularly mercaptobenzothiazole act as powerful accelerators of vulcanization tion without scorching. the stock.

when incorporated in rubber and subjected tov heat and pressure. The dithiazyl monosulfides derived therefrom, as for example, ,dibenzothiazyl monosulfide, are occasionally used instead, largely because they are free from the tendency of the mercaptothiazoles to scorch the stocks in which they are employed. They are, however, slower than and therefore'inferior to the mercaptothi azoles as accelerators of vulcanization.

One of the objects of, ourinvention isto increase the somewhat limited usefulness as accelerators of those and other dithiazyl monosulfides.

Among other things, ourinvention involves the discovery that a basic nitrogen compound such as ammonia, an amine or a Schifis base, added to the rubber mix either together with the desired dithiazyl monosulfide or separately, has the effect of enhancing theaccelerative power of the dithiazyl monosulfide without detracting from the ability of the latter to accelerate vulcaniza- Mixtures of these nitrogen compounds ,with the dithiazyl monosulfides constitute accelerators of great power. They do not cause premature vulcanization at the temperatures involved in the milling steps, but when subjected'to the proper degree of heat bring about active vulcanization.

Dibenzothiazyl monosulfide, which is illustrative of the dithiazyl monosulfides generally in the practice of our invention, may be' represented as follows: i

In thisformula, the characters 3,-3.1, Re and R3 indicate the position of possible substituents,

Application February 25, 1932, Serial No. 595,218

stituted monosulfides, by-employing a substituted chlor benzothiazole and/or a substituted benzothiazyl sulphide. The substituents R, R1, R2 and R3 may be similar or dissimilar radicals selected from a group including nitro, amino, phenyl, ethyl, methyl, bromine, chlorine and other radicals.

Examples of organic bases which may be employed to activate the dithiazyl m'onosulfides are diphenylguanidine, triphenyl guanidine, diortho tolyl guanidine, 'dicyclo hexyl guanidine, hexamethylene tetramine, dicyclo hexyl piperazinc, piperazine, piperidine, ethylene diamine, the polyethylene diamines, allyl amine, propyl amine, heptyl amine, benzyl amine, isoamyl amine, dibutyl amine, phenyl ethyl amine, methyl cyclo hexyl amine, alpha carbo diphenyl di-imid and amino ethyl alcohol. Schiffs bases, which may be employed with satisfactory results, include crotonylidene aniline, butylidene aniline, aldol aniline, ethylidene aniline, methylene aniline, methylene toluidine and methylene xylidene. Formaldehyde, 'acetaldehyde and other aldehyde derivatives of Schifis bases are also suitable;

likewise, the bases formed by the interaction of aliphatic amines such as ethyl amine, ethylene diamine, propyl amine, and similar amines with such aldehydes as acetaldehyde, propionaldehyde, butyraldehyde, crotonaldehyde and the aldols.

In mixtures of the dithiazyl monosulfides with these organic bases, it is preferable to use from 10 to percent of organic base. .The compounds may be mixed prior to incorporatingthem in the rubber mix or they may be milled separately into the rubber. In either case, they may be employed in standard rubber formulae. 1 The following is an illustrative example of a formula in which they have been found by actual test to be satisfactory:

, q Parts Rubber Zinc oxide 5 Sulfur n 3 Stearic acid 1.5 Accelerator .5

In this formula, the relative proportions of the two compounds may vary over a wide range, although 40 percent of the dithiazyl monosulfide is to be preferred. For testing the efficacy of the accelerator, samples of rubber prepared in accordance with the above formula were subjected to vulcanization for varying periods of time. The samples were then subjected to physical tests in order to ascertain the tensile strength and elas ticity thereof. Results of these tests are tabulated as follows:

Cure Stress kgs/cm at Tens. g e tri't 5007 W ime 1n gs cm mins. i elong clong 40% fi-mono nitro dibenzothiazyl monosulfide 60% crotonylidene aniline 40% 6-n10no nitro dibenzothiazyl monosulfide 60% diphenylguanidine 40% fi-nitro B-chloro dibenzothiazyl monosulfide 60% dipl enylguanidine 20 .260 940 10 28 40 260 750 30 120 80 .260 '220 700; 54' 220 60 285 216 715 53 .205 40% 66 dinitro 5echlor dibenzothiazyl:monosulfide 60% diphenylguanidine 20 260 102 945 11 p .28 4O 7 260 144 745 28 110 80 260 221 715 50 205 00 285. 208 I 710 50 198 40% 6-nitro 5-chlor dibcnzothiazylmonosulfide 60% crotonylidene aniline I j 20 260 114 875 15 46 40 260 164 .775 '30. 114 80, 260 200 .725 45 y 60 285 V 725 V 41 155 40% 6-6 dinitro'5-chloro dibenzothiazyl monosulfide 00% crotonylidene aniline .20 260 106 725 a 15 42 940 260 V 154 .885 25 90' 80 260 800 35 V p 132 60- 285 167 755 I 40 140 =Obvious'ly, the dithiazyl monosulfide and the organic 'base herein employed conjo'intly as the accelerator may be manufacturedwithout the use off-complicated orexpensive apparatus. The materials are in most cases solids which do not tend to scorch the stock and which may be introduced into rubber compounds without excessive milling. Their use gives r-ise {to products of good tensile strength and elasticity. In view of these facts and of the absence of any noticeable toxicity. these compounds are'highlydesi-rame as commercial accelerators;

"ilhe above examples of the practice of the invention are to be regarded as illustrationsonly, forzit will be understood thatvarious changes may be made by persons skilled in the art without departing from the spirit of the invention. It isdesired to embrace such modifications and changes as may be necessary to adaptto varying conditions and uses. It is intended that the patent shall cover, by suitable expression in the appended claims, whatever features of patentable novelty reside in the invention herein disclosed. What'we claim is: V

1. A method of treating rubber which comprises yulcaniz'ing it in the presence of a di(aryl thiazyl) monosulfide and an accelerating amine.

2. A method of treating rubber which comprises subjecting it to'vulcanization in the presence of a di(benzo thiazyl) monosulfide and an accelerzaiting organic base.

A method of treating rubber which comprises subjecting it to vulcanization in the presence of a di(aryl thiazyl) monosulfide and a gen-containing compound. v

4. A method of treating rubber which comprises subjecting it to vulcanization in the presence of a di(ary1thiazyl) monosulfide and a Schiffs base. 5. A method of treating rubber which comprises subjecting it to vulcanization in the presence of a mixture of a dibenzenoid thiazyl monosulfide. and an organic base. 1

*6. A method of treating rubber which. comprises subjecting :it to vulcanization the presence of a nitro-di(aryl thiazyl) monosulfide an lansamine. 7. A method of treating rubber which comprises basic nitrosubjecting it to vulcanization in the presence of 'a-di(ary1.thiazyl-) monosulfide and crotonylidene .aniline.

8. .r-Aimethodxcf treating rubber which comprises 7 subjecting it to vulcanization in the presence of a di(arylthiazyl) monosulfide and a poly aryl :guan'rdine;

9. A method of treating rubber which coml prises subjecting it to vulcanization in the "presence of a di(arylthiazy1) monosulfide and a poly p'heny kguanidine. I I

10. A method of treating rubber which comprises subjecting it to vulcanization in the presence of a mixture of a -di ('aryl thiazyl) mono 611:1": fideanddiphenylguanidine.' r 'f I 11; rubber product that has been vulcanized in the presence of di (benzo thiazyl);-mono sulfide and an accelerating organic base.

. 12. A rubber product that has been vulcanized in the presence of di(-benzo'thiazyl') mono' sulfide and an accelerating organic base. a

13. A rubber product that has been vulcanized in the presence-of a d-i-(aryl thiazyl) mono sulfide h and a basic nitrogen-containing compound;

14. A vulcanizable rubber composition comprising, combination, a; rubber 'stock;containing amixture =of a :ditaryl thiazyl) mono sulfide and an acceleratingorganic base.

'15. A rubber product that has been vulca'niz'ed in the presence of an accelerating organic base and a'nitrodibenzothiazyl monosulfide.

16. The process of treating rubber which com prises combining said rubber with a vulcanizing agent and a smallqproportion of a nitro ben'zothiazyl monosulfide. admixed with a complementary organic accelerator of basic nature.

1 7. A rubber product that hasbeen vulcanized in the presence of a 6-6' dinitro dibenzothiazyl monosulfide and a-poly-aryl guanidine.

18. The process of treating rubber which comprises vulcanizing in the presence of an acceler ating organic base and formula ent replacing hydrogen.

19. A vulcanizable rubber composition comprisa compound having the ing, "in combination, a rubber stock containing a di-benz'othiazyl monosulfideand amine accelerator. v V Y I '20. The process of treating rubberwhich comprises vulcanizing it in the presence of a mono nitro dibenzothiazyl monosulfide and a Schifis base; I

21. The process of treating rubber which comprises vulcanizing in the presence of a nitro di an aldehyde-r (benzothiazyl) mono sulfide and a basic organic nitrogen-containing compound.

22. The process of treating rubber which comprises vulcanizing in the presence of di(benzothiazyl) mono sulfide and a. diaryl guanidine.

23. The process of treating rubber which comprises vulcanizing in the presence of di '(benzothiazyl) mono sulfide and a basic organic nitrogen-containing compound.

24. The process of treating rubber which comprises vulcanizing in the presence of a chlor di (benzothiazyl) mono sulfide and a basic organic nitrogen-containing compound.

25. A rubber product which has been vulcanized in the presence of a nitro di (benzothiazyl) mono sulphide and abasic organicnitrogen-containing compound.

26. A rubber product which has been vulcanized in the presence of di (benzothiazyl) mono sulfide and a diaryl guanidine.

27. A rubber product which has been vulcanized in the presence of di (benzothiazyl) mono sulphide and a basic organic nitrogen-containing compound.

28. A rubber product which has been vulcanized in the presence of a di (aryl thiazyl) mono sulphide and an accelerating amine 

